For those who don't know, ALS (AKA amyotrophic lateral sclerosis or Lou Gehrig's disease), is a horrific condition which weakens the body's muscles until it can no longer function. At this time, the disease has no cure.

According to Hadid, Ellie sadly succumbed to her illness despite an amazing fight. O'Connell was hanging on to see her daughter graduate college in 2017, a wish which will tragically go unfilled.

Despite the heartbreak, the model did her best to honor her close pal's legacy in a touchingInstagrampost: